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A. Adare, 13 S. Afanasiev, 31 C. Aidala, 40, 44, 45

We evaluate the exposure during nadir observations with JEM-EUSO, the Extreme Universe Space Obser-\ud vatory, on-board the Japanese Experiment Module of the International Space Station. Designed as a mis-\ud sion to explore the extreme energy Universe from space, JEM-EUSO will monitor the Earth’s nighttime\ud atmosphere to record the ultraviolet light from tracks generated by extensive air showers initiated by\ud ultra-high energy cosmic rays. In the present work, we discuss the particularities of space-based obser-\ud vation and we compute the annual exposure in nadir observation. The results are based on studies of the\ud expected trigger aperture and observational duty cycle, as well as, on the investigations of the effects of\ud clouds and different types of background light. We show that the annual exposure is about one order of\ud magnitude higher than those of the presently operating ground-based observatories

High energy proton-and deuteron-nucleus collisions provide an excellent tool for studying a wide array of physics effects, including modifications of parton distribution functions in nuclei, gluon saturation, and color neutralization and hadronization in a nuclear environment, among others. All of these effects are expected to have a significant dependence on the size of the nuclear target and the impact parameter of the collision, also known as the collision centrality. In this article, we detail a method for determining centrality classes in p(d) + A collisions via cuts on the multiplicity at backward rapidity (i.e., the nucleus-going direction) and for determining systematic uncertainties in this procedure. For d+Au collisions at √ s N N = 200 GeV we find that the connection to geometry is confirmed by measuring the fraction of events in which a neutron from the deuteron does not interact with the nucleus. As an application, we consider the nuclear modification factors R p(d)+A , for which there is a bias in the measured centrality-dependent yields due to auto correlations between the process of interest and the backward-rapidity multiplicity. We determine the bias-correction factors within this framework. This method is further tested using the hijing MC generator. We find that for d+Au collisions at √ s N N = 200 GeV, these bias corrections are small and vary by less than 5% (10%) up to pT =10 (20) GeV/c. In contrast, for p+Pb collisions at √ s N N = 5.02 TeV we find these bias factors are an order of magnitude larger and strongly pT dependent, likely due to the larger effect of multiparton interactions.

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